• 한국환경보건학회지
• /
• 제22권2호
• /
• pp.32-42
• /
• 1996

This study was performed to evaluate accuracy and precision of filter method and impinger method for analyzin airborne isocyanates in mixture (2, 6-TDI, HDI, 2, 4-TDI, MDI). Filter method was performed using the OSHA Method 42 and impinger method using the NIOSH Method 5521. The samples were analyzed by high performance liquid chromatography-ultraviolet detector (HPLC-UVD). After the optimum operating conditions for each method were investigated, samples with various concentration levels were quantified at the conditions. The precision was expressed by the pooled coefficient of variation(C.V.) and the accuracy by overall accuracy. The results are summarized as follows: 1. The optimum condition of filter method was determined at 35/65 ACN/buffer (0.01 M ammonium acetate) in mobile phase. And in case of impinger method, it was at 30/70 ACN/buffer(0.2 M sodium acetate). The effect of concentrations of acetate on the separation of the peaks was not significant, but, the effect of ACN/buffer ratio was significant. 2. The correlation coefficients for the two methods were above 0.9 in all isocyanate compounds. Average recovery efficiencies for 2, 6-TDI, HDI, 2, 4-TDI and MDI in filter method were 92.4%, 102.6%, 87.3% and 101.0%, respectively. Those in impinger method were 106.6%, 106.7%, 99.0% and 103.6%, respectively. As a result, the recovery efficiency of impinger method was higher than those of filter method in analyzing isocyanate compounds. 3. The pooled coefficients of variations of the methods were slightly higher than expected. The overall accuracies of the methods were within $\pm 25%$ for each isocyanate compound. Since these results satisfy NIOSH criteria, the accuracy of the experiment is appropriate. 4. As seen above, impinger method is more efficient than filter method. But, there are many disadvantages in impinger method. Therefore, solid sorbent such as a glass fiber filter must be developed in order to have the high efficiency not less than that of impinger method in the future.

• 생명과학회지
• /
• 제20권1호
• /
• pp.60-65
• /
• 2010

파속류에 다량 함유된 황화합물들은 GC/ECD에 민감하게 반응하기에, 이 농산물들의 잔류농약분석에서 방해 물질로 작용하여 농약성분의 분리정량에 어려움을 주고 있다. 최근 잔류농약분석에서 정제법으로 여러 가지 고상추출법(solid-phase extraction)이 개발되고 있으며, 본 연구에서는 황화합물을 효율적으로 제거하기 위하여, 20% 질산은($AgNO_3$)용액 3 ml을 Florosil cartridge (1 g packing, 6 ml tube)에 처리한 은이온흡착 cartridge (silver nitrate impregnated florosil cartridge)를 조제하였다. 이 cartridge를 이용하여 파속류 각 2, 4, 6 및 10 g에 해당하는 추출액을 고상추출법으로 정제한 결과, 양파 6 g, 대파 4 g, 쪽파는 4 g 까지는 황화합물의 95% 이상을 제거할 수 있었다. 그리고, 40종의 농약을 각 파속류에 첨가하고 이 cartridge에서 유출하여 회수율을 분석한 결과 34종이 70~120%의 범위 안에 들었다.

• Asian-Australasian Journal of Animal Sciences
• /
• 제33권9호
• /
• pp.1520-1532
• /
• 2020

Objective: Due to rapid economic return, mixed crop-swine farming systems in Korea have become more intensive. Intensive farming practices often cause nutrient surpluses and lead to environmental pollution. Nutrient budgets can be used to evaluate the environmental impact and as a regulatory policy instrument for nutrient management. This study was conducted to select a nutrient budgeting approach applicable to the mixed crop-swine farms in Korea and suggest an effective manure treatment method to reduce on-farm nutrient production. Methods: In this study, we compared current and ideal gross nutrient balance (GNB) approaches of Organisation for Economic Co-operation and Development and soil system budget (SSB) approach with reference to on-farm manure treatment processes. Data obtained from farm census and published literature were used to develop the farm nutrient budgets. Results: The average nitrogen (N) and phosphorus (P) surpluses were approximately 11 times and over 7 times respectively higher in the GNB approaches than the SSB. After solid-liquid separation of manure, during liquid composting a change in aeration method from intermittent to continuous reduced the N and P loading about 50% and 47%, respectively. Although changing in solid composting method from turning only to turning+aeration improved the N removal efficiency by 30.5%, not much improvement in P removal efficiency was observed. Conclusion: Although the GNB approaches depict the impact of nutrients produced in the mixed crop-swine farms on the overall agricultural environment, the SSB approach shows the partitioning among different nutrient loss pathways and storage of nutrients within the soil system; thus, can help design sustainable nutrient management plans for the mixed cropswine farms. The study also suggests that continuous aeration for liquid composting and turning+aeration for solid composting can reduce nutrient loading to the soil.

• 유기물자원화
• /
• 제18권4호
• /
• pp.64-68
• /
• 2010

최근, 국내에서 MBT(Mechanical Biological Treatment) 처리시설이 건설되어 운영 중에 있으며, 생활폐기물 등이 분리선별되어 재활용되고 있다. 그러나, 생활폐기물의 입도가 불균질하고, 분리선별을 하기 위해서 일정입도 이하로 파쇄하여야 하므로 운영상의 문제점이 발생하게 된다. 또한, 생활폐기물내 유기성분의 분리선별이 어려워서, 재활용 물질의 이용이 어려운 실정이라 이에 대한 대책이 요구된다. 본 연구에서는 1ton/batch 규모의 반응기에 과열증기를 사용하여 각 반응인자에 따른 생활폐기물 분리선별 효율을 파악하였으며, 유기성분 분해에 따른 생활폐기물 입도특성의 변화를 고찰하였다.

• 토지주택연구
• /
• 제2권1호
• /
• pp.87-92
• /
• 2011

음식물폐기물 처리 과정에서 발생되는 음폐수의 효율적인 처리를 위한 혐기소화공정을 선정하기 위하여, 단상 및 이상혐기소화공정을 대상으로 데모플랜트(일 5톤 처리용량)를 활용하여 성능을 비교하였다. TS, VS, tCOD 및 sCOD 처리율을 비교하여 보면 모든 항목에서 단상혐기소화공정의 처리율이 우수하였지만, 바이오가스는 오히려 이상혐기소화공정에서 더 많이 발생하였다. 이는 단상혐기소화공정의 경우 운전기간 동안 음폐수 투입량이 상대적으로 적어 처리효율은 뛰어 났지만, 음폐수 투입량 변동에 따른 바이오가스의 발생이 민감하게 반응을 한 결과로 해석된다. 이상혐기소화공정의 경우 총 COD가 상대적으로 매우 낮은 수준임에도 불구하고 바이오가스 발생량은 단상혐기소화공정보다 많이 발생되었다. 이는 음폐수 투입량이 일정하게 유지되었고, 산발효공정과 메탄발효공정이 분리되어 운영됨으로써 공정 전체가 안정적으로 운영되었기 때문인 것으로 판단된다. 음폐수처리를 위해서는 공정 선정이 중요하지만 단순 유기물처리율 비교만으로는 종합적인 평가가 어려우며, 이를 보완하기 위하여 원료성상, 투입량, 처리율, 운전기간, 바이오가스발생량 등을 종합하여 소화성능을 평가하여야 할 것이다.

• 대한환경공학회지
• /
• 제22권2호
• /
• pp.279-289
• /
• 2000

본 연구에서는 정수공정에서 응집제 종류와 고액분리방법이 조류제거에 미치는 영향을 조사하였다. 따라서, 원수의 특성을 탁도, $KMnO_4$ 소비량, UV-254, chlorophyll-a 등으로 파악하고 이들 수질인자간의 상관관계를 분석하였다. 또한 시판중인 Alum계열 응집제(Alum, PAC, PACS)가 조류제거에 미치는 영향을 실험실 쟈테스트를 이용하여 탁도 및 유기물제거, pH 저하특성 및 알카리도 소모특성 및 개체수 제거율 등으로 연구하였다. 상관관계 분석에 의하면 유기물항목인 UV-254, $KMnO_4$ 소비량, chlorophyll-a와 탁도의 상관계수는 각각 0.775, 0.674 및 0.623으로 상관성이 매우 높은 것으로 나타났다. 조류발생시 응집제 종류별 응집침전에서 유기물 제거특성은 조류의 농도가 적을 경우에는 유사한 효율을 보였으나 조류농도 증가에 의한 높은 유기물 농도($KMnO_4$ 소비량 20mg/l 이상)와 높은 탁도(100NTU 이상)에서는 PAC, PACS와 같은 무기고분자 응집제가 Alum보다 제거효율이 우수하였다. 조류번성시 응집공정을 거친 후 침전과 부상공정의 비교실험에서 부상분리공정을 사용할 경우 Alum이 모든 분석항목에서 고분자 응집제인 PAC, PACS보다 우수하였으며, 95% 이상의 제거율을 나타내었다. 반면에 PAC와 PACS의 경우는 침전공정이 부상공정보다 효율이 높았으며, $KMnO_4$ 소비량의 경우 부상법 제거율의 2배 이상 효율을 보여주었다. 따라서 조류제거를 향상시키기 위해서는 Alum을 사용할 경우 부상분리, PAC, PACS를 사용할 경우 침전공정이 바람직한 것으로 나타났다. 대상원수에서는 남조식물문의 Microcystic와 녹조식물문의 pediastrum simplex 등 두 가지의 속이 다수 속으로 출현하였으며, Alum, PAC, PACS의 투입후 침전실험에서 27%, 45%, 22%의 조류개체수의 제거율을 보였으나, 용존공기부상법(DAF)을 적용한 경우에는 모든 응집제에서 동, 식물플랑크톤 모두가 100%에 가까운 제거율을 보여주었다.

• 상하수도학회지
• /
• 제8권1호
• /
• pp.1-8
• /
• 1994

Laboratory experiments were conducted to investigate the effect of digestion temperature on the settleability and dewaterability of anaerobically digested sludge. The digesters were operated at a hydraulic retention time of 20 days with a loading rate of 0.63~0.66kg volatile solids per cubic meter per day at the temperature of $35^{\circ}C$ and $55^{\circ}C$. A mixed primary and secondary municipal sludge was used as a feed. The interface height of the sludge during settling test was recorded to identify settleability. As a measure of dewaterability of the sludge, specific resistance and capillary suction time were also measured with and without chemical conditioning. Higher digestion efficiency was obtained at $55^{\circ}C$ than $35^{\circ}C$. However, the settleability and dewaterability of the sludge at $35^{\circ}C$ were quite higher than those of the sludge digested at $55^{\circ}C$. The optimum dosages of ferric chloride for sludge conditioning were 0.4% and 0.6% at $35^{\circ}C$ and $55^{\circ}C$, respectively. The filtrate COD of the sludge digested at $55^{\circ}C$ was higher than at $35^{\circ}C$, which means that poor dewaterability of the sludge result in high filtrate COD.

• 상하수도학회지
• /
• 제22권2호
• /
• pp.179-182
• /
• 2008

The KIDEA process, occurred in single reactor, is operated by three consequential steps, i.e., aerobic, settling, and discharge while introducing wastewater into the bottom of reactor continuously. It could accomplish biological oxidation (BOD), nitrification, denitrification (T-N), phosphate removal (T-P), and solid separation (SS) through the operational mode mentioned. Especially, this system has removed the T-P by wasting certain amount of sludge at the end of aeration phase during 5~10 minutes and not returned the activated sludge into the reactor, that is, no RAS (Return Activated Sludge). All running mode and instrumentation were controlled by the PLC equipment automatically. In this study, therefore, we have evaluated T-P removal efficiency and moisture content (MC) performance under the different excess sludge wasting mode. T-P track study and MC with TS concentration were analyzed during aerobic and settling phase. It has revealed that there was no significant difference of released T-P concentration between the first case which waste the sludge at the end of aerobic phase (0.2mg/L) and the second case which waste the sludge at 40 min of settling phase (0.25mg/L). Also, dewatering duration and MC have decreased 1.7% when TS concentration was increased from 0.31% to 0.5% during aerobic condition. Hence, it has concluded the system performance was less influenced by the operation time change of PLC program.

• 대한설비공학회:학술대회논문집
• /
• 대한설비공학회 2009년도 하계학술발표대회 논문집
• /
• pp.1379-1384
• /
• 2009

High power light emitting diode(LEDs), a strong candidate for the next generation general illumination applications are of interest. With major advantages of power saving, increased life expectancy and faster response time over traditional incandescent bulb, the LEDs are rapidly taking over many applications such as LCD backlighting, traffic light, automotive lighting, signage, etc. The increased electrical currents used to drive the LEDs have focused more attention on the thermal management because the efficiency and reliability of the solid-state lighting devices strongly depend on successful thermal management. There exist some problems that are caused by heat generation in the LED package, such as wire breakage, yellowing of epoxy resin, lifted chip caused by reflow of thermal paste chip attach and interfacial separation between LED package and silicon resin. The goal of this study is to analyze high power LED thermal properties of using pulsating heat pipe.

• 대한기계학회논문집B
• /
• 제33권5호
• /
• pp.299-310
• /
• 2009

Fuel cells are expected to be promising future power sources in both aspects of thermal efficiency and environmental friendliness. Accordingly, worldwide research and development efforts have been enormously increasing recently in various applications such as power plants, transportation and portable power sources. Among others, high temperature fuel cells, such as solid oxide fuel cells and molten carbonate fuel cells, are suitable for electric power plants. Moreover, their high operating temperature is quite appropriate to construct further advanced integrated systems. This paper reviews recent literatures on research and development of integrated power generation systems based on high temperature fuel cells. Research and development efforts are summarized in the area of fuel cell/ gas turbine hybrid systems, application of carbon capture technology to fuel cell systems, integration of coal gasification with fuel cells, and the use of alternative fuels.